Hand-held Calculators

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Otis King Type L

The Otis King calculator was sold into the 1970s and was advertised in competition with the early electronic hand-held calculators, so is included as a comparison with the electronic calculators with which it competed.

Otis King Model L

Otis King calculator extended.

Otis King Model L.

Distinctive features: Cylindrical slide rule.

Technical details:
Although described as a calculator (see top photograph) this is really a cylindrical slide rule. By forming it as a cylinder the effective length of the slide rule scale is 66 inches long.

153 mm closed, 262 mm extended, x 31 mm diameter
(6" closed, 10.3" extended, x 1.25" diameter).

"British made throughout".

Carbic Limited,
171, Seymour Place,

There were two versions of this calculator - the Model K and the Model L which had an additional scale for determining logarihms.

An advertisement for the model L in February 1971 gives a price of 85s (4-25p [about $10-50]), which was a fraction of the cost of an electronic calculator (see Bowmar 901B/Commodore C110 at 79 [approx. $195]).
One of the last advertisements for an Otis King calculator (actually the model K) in August 1973 gives a price of 4-65p [about $11-50], which was now comparable to the cost of the cheapest electronic calculator.

The story of Otis King calculators is told in "Otis King Calculators: A History of Production, 1919-1977", by and published by Colin Barnes, ISBN 0 9535039 0 9 - see the United Kingdom Slide Rule Circle's site at http://www.uksrc.org.uk/publications2015.pdf.

Otis King Model L
Otis King Model L

Otis King calculator closed

Otis King Model L

Otis King calculator extended

Otis King calculator, closed in its box.

The Otis King calculators were popular for many years and continued to sell into the era of electronic calculators due to their very low cost.

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Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.